Numerous reports on skeletal muscle metabolism have been published over the past 15 years, but the data on smooth muscle metabolism especially that of primate myometrium are extremely space. We are investigating the effects of prostaglandins on the adenylate cyclase activity of myometrium from pregnant rhesus monkeys (Macaca mulatta) and from ovariectomized monkeys during an artificial menstrual cycle. Ten micrograms of estradiol were injected twice daily for 11 days and 10 micrograms of estradiol plus 0.75 mg of progesterone were similarly administered for the next 18 days. The levels of c-AMP, ADP, and AMP and phosphodiesterase activity in myometrium from these preparations will also be determined. Since cyclic AMP levels are closely linked to the control of rate- limiting enzymes such as phosphofructokinase, prostaglandins may exert an indirect effect on glycolysis. We are using several approaches to the study of rate-limiting enzymes: 1) We are comparing the rates of product formation from various precursors and intermediates; e.g., lactate-C14 formation from different labelled precursors in the glycolytic pathway, such as glucose, glucose-6-P... 2) We are measuring the production of lactate-C14 from C14-labelled precursors such as fructose-6-PO4 both with and without effector molecules such as ATP, Pi, and c-AMP. Our laboratory has demonstrated that lipid as well as carbohydrate serves as an energy source for myometrium. Therefore, the effect of citrate on this system will be tested. 3) We are also determining mass-action ratios in situ for the glycolytic pathway and comparing these ratios with the apparent equilibrium constants. The effects on altered glycolytic flux rate on the intracellular contents of relevant metabolic intermediates will also be investigated. These studies will enable us to evaluate the rate-limiting reactions in smooth muscle and to determine the influence of protaglandins and eventually hormones such as estrogen and epinephrine on the metabolism of this tissue.